﻿#include <iostream>
#include <cstring>
#include <queue>
using namespace std;
const int N = 1010;
int dx[4] = { 0, 0, 1, -1 };
int dy[4] = { 1, -1, 0, 0 };
int n, m;
int x1, y1, x2, y2;
char arr[N][N];
int dist[N][N]; // [i, j] 位置是否已经搜索过，以及到达 [i, j] 位置的最短距离  
int bfs()
{
	if (arr[x2][y2] == '*') return -1;

	memset(dist, -1, sizeof dist); // 表⽰还没开始搜索 
	queue<pair<int, int>> q;
	q.push({ x1, y1 });
	dist[x1][y1] = 0;
	while (q.size())
	{
		auto [a, b] = q.front();
		q.pop();
		for (int i = 0; i < 4; i++)
		{
			int x = a + dx[i], y = b + dy[i];
			if (x >= 1 && x <= n && y >= 0 && y <= m && arr[x][y] == '.' &&
				dist[x][y] == -1)
			{
				q.push({ x, y });
				dist[x][y] = dist[a][b] + 1;
				if (x == x2 && y == y2) return dist[x2][y2];
			}
		}
	}
	return -1;
}
int main()
{
	cin >> n >> m >> x1 >> y1 >> x2 >> y2;
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			cin >> arr[i][j];
		}
	}
	cout << bfs() << endl;
	return 0;
}